“To summarize our conclusions, a trial court may exercise its inherent authority consistent with due process to issue a subpoena or an order for a victim or a witness to attend a non-invasive physical or mental examination. Such a discovery order should be issued rarely, only upon a showing by the defendant of a compelling or substantial need for the examination. Defendant must demonstrate that comparable evidence is not available through another source, and that the benefit to the defendant clearly outweighs the hardship or inconvenience to the victim or the witness. Normally, any punishment for refusal should not fall upon the victim, but consequences can be imposed upon the State. Finally, any such order should include provisions to avoid any expense to the victim and to minimize other monetary loss or inconvenience.”